There has been developed heretofore driving assistance systems that detect a solid object existing in front of the self-vehicle and, if a collision of the self-vehicle with the detected solid object is predicted to occur, warns the driver or automatically performs driving operations for avoiding a collision of the self-vehicle with the solid object.
In a known technology pertaining to the driving assistance system as described above, a solid object existing around the self-vehicle is detected using a camera, a laser radar, or the like, and assistance for steering and/or braking operation is performed based on the degree of risk determined in relation to the type of the solid object and the time to collision (TTC) (see, for example, Patent Document 1).